Range imaging system and solid-state imaging device

ABSTRACT

A range imaging system includes: a control unit that generates a light emission signal for instructing light irradiation and an exposure signal for instructing exposure; a pulsed-light source unit that emits pulsed light in response to the light emission signal; an imaging unit that includes a solid-state imaging device and performs exposure and imaging in response to the exposure signal; and a calculation unit that calculates range information. The solid-state imaging device includes a first pixel for receiving radiant light from a subject and a second pixel for receiving reflected light of the pulsed light. The calculation unit calculates the range information using an image capture signal from the first pixel and an imaging signal from the second pixel.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of PCT International Application No.PCT/JP2014/005821 filed on Nov. 19, 2014, designating the United Statesof America, which is based on and claims priority of Japanese PatentApplications No. 2013-240310 filed on Nov. 20, 2013 and No. 2014-009860filed on Jan. 22, 2014. The entire disclosures of the above-identifiedapplications, including the specifications, drawings and claims areincorporated herein by reference in their entirety.

FIELD

The present disclosure relates to a range imaging system and asolid-state imaging device.

BACKGROUND

Various kinds of ranging systems have been proposed. Among these rangingsystems, a conventional ranging system disclosed in Patent Literature 1includes the following: a control unit that integrally controls theother units; an infrared (IR) light emitting unit that emits IR lighttoward an imaging target space; a lens that condenses visible light andIR light from the imaging target space; and a solid-state imaging devicethat photoelectrically converts the light condensed by the lens into apixel signal and outputs the pixel signal. Using these structuralelements, this ranging system forms a visible light image and a rangeimage.

FIG. 32 is a functional block diagram showing a schematic configurationof a conventional ranging system. As shown in FIG. 32, a solid-stateimaging device included in the ranging system includes the following: aB light receiving unit that receives blue (B) light and accumulatesB-signal charge; a G light receiving unit that receives green (G) lightand accumulates G-signal charge; an R light receiving unit that receivesred (R) light and accumulates R-signal charge; and an IR light receivingunit that receives infrared (IR) light and accumulates IR-signal charge.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. 2008-8700

SUMMARY Technical Problem

According to the conventional technique disclosed in Patent Literature1, however, a visible light image is formed using the signals from theB, G, R light receiving units and a range image is formed using thesignal from the IR light receiving unit. Here, note that a distancecalculated from the range image is limited to a distance to a subjectimage. Moreover, image processing using the subject image and the rangeimage to separately read the visible light image and the range imageincludes only image synthesis in which an image of a person is extractedfrom the image to change the background.

In other words, ranging disclosed in Patent Literature 1 is performedusing only the range image formed by the signal from the IR lightreceiving unit, thereby providing low ranging performance.

In view of the aforementioned problem, one non-limiting and exemplaryembodiment provides a range imaging system and a solid-state imagingdevice having high ranging performance.

Solution to Problem

To solve the aforementioned problem, a range imaging system according toan aspect of the present disclosure includes: a signal generation unitwhich generates a light emission signal for instructing lightirradiation and an exposure signal for instructing exposure; apulsed-light source unit which emits pulsed light in response to thelight emission signal; an imaging unit which includes a solid-stateimaging device and performs exposure and imaging in response to theexposure signal; and a calculation unit which calculates rangeinformation, wherein the solid-state imaging device includes a firstpixel for receiving radiant light from a subject and a second pixel forreceiving reflected light of the pulsed light, and the calculation unitcalculates the range information using an image capture signal from thefirst pixel and an imaging signal from the second pixel.

Moreover, the calculation unit according to an aspect of the presentdisclosure may calculate a dimension of the subject, using a distance tothe subject calculated from the image capture signal and the imagingsignal.

Furthermore, the range imaging system according to an aspect of thepresent disclosure may include a detection unit which detects at leastone subject from a whole subject scene using the image capture signal.The pulsed-light source unit may perform the light irradiation on thedetected subject. The calculation unit may calculate a distance to thesubject, as the range information, using the imaging signal.

Moreover, the range imaging system according to an aspect of the presentdisclosure may include a detection unit which detects at least onesubject from a whole subject scene using the image capture signal. Thepulsed-light source unit may perform the light irradiation on thedetected subject. The calculation unit may calculate a distance to thesubject using the imaging signal, and further calculate a dimension ofthe subject using the imaging signal and the distance to the subject.

Furthermore, the pulsed-light source unit according to an aspect of thepresent disclosure may irradiate a partial region of the subject withthe pulsed light. The calculation unit may calculate the distance to thesubject and the dimension of the subject, on the basis of the partialregion of the subject.

Moreover, the range imaging system according to an aspect of the presentdisclosure may be mounted to transportation equipment, and the subjectmay be another piece of transportation equipment. The range imagingsystem may perform at least a part of drive control of thetransportation equipment mounted to the range imaging system, using adistance to the other transportation equipment.

Furthermore, the range imaging system according to an aspect of thepresent disclosure may be mounted to portable equipment, and thecalculation unit may calculate the dimension of the subject displayed ona display unit of the portable equipment.

Moreover, the pulsed-light source unit according to an aspect of thepresent disclosure may include a line lens.

Furthermore, the range imaging system according to an aspect of thepresent disclosure may include a second light source which emits lightsynchronizing with the pulsed light emitted to the subject.

Moreover, the range imaging system according to an aspect of the presentdisclosure may include a detection unit which detects a state of aranging environment using the image capture signal. The calculation unitmay select between the image capture signal and the imaging signal tocalculate the range information, according to the state of the rangingenvironment, or may correct one of the image capture signal and theimaging signal using the other one of the image capture signal and theimaging signal to calculate the range information, according to thestate of the ranging environment.

Furthermore, the calculation unit according to an aspect of the presentdisclosure may select between the image capture signal and the imagingsignal to calculate the range information, on the basis of informationstored in the range imaging system, or may correct one of the imagecapture signal and the imaging signal using the other one of the imagecapture signal and the imaging signal to calculate the rangeinformation.

Moreover, the calculation unit according to an aspect of the presentdisclosure may calculate the range information by comparing a currentframe with a preceding frame using the image capture signal.

Furthermore, the range imaging system according to an aspect of thepresent disclosure may select between the image capture signal and theimaging signal to calculate the range information, on the basis of animaging magnification, a time of day or night, a weather condition, adistance to the subject, or a motion speed of the subject or the rangeimaging system.

Moreover, the range imaging system according to an aspect of the presentdisclosure may be mounted to transportation equipment.

Furthermore, the calculation unit according to an aspect of the presentdisclosure may calculate a distance by a time-of-flight method.

Moreover, the pulsed-light source unit according to an aspect of thepresent disclosure may emit laser light.

Furthermore, the pulsed-light source unit according to an aspect of thepresent disclosure may include a single-color light emitting element ora multi-color light emitting element.

Moreover, according to an aspect of the present disclosure, the firstpixel may receive visible light and the second pixel receives lightother than the visible light.

Furthermore, according to an aspect of the present disclosure, the lightother than the visible light may be infrared light.

Moreover, according to an aspect of the present disclosure, the firstpixel may further receive reflected light of the pulsed light and thesecond pixel may further receive radiant light from the subject.

Furthermore, the pulsed-light source unit according to an aspect of thepresent disclosure may include a light source and a light-source movingunit. The light-source moving unit may divide source light from thelight source and emit a plurality of pulsed light beams.

Moreover, the light-source moving unit according to an aspect of thepresent disclosure may be a diffraction grating.

Furthermore, the range imaging system according to an aspect of thepresent disclosure may determine irradiation directions of the pulsedlight beams, arrangement of irradiation points of the subject, or shapesof the pulsed light beams, on the basis of the image capture signal.

Moreover, according to an aspect of the present disclosure, the pulsedlight beams may be emitted at inconstant periodic timings orindividually unique timings.

Furthermore, according to an aspect of the present disclosure, the rangeinformation may be calculated using dispersion of the pulsed lightbeams.

Advantageous Effects

A range imaging system according to the present disclosure can achievehigh ranging precision.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features will become apparentfrom the following description thereof taken in conjunction with theaccompanying drawings, by way of non-limiting examples of embodimentsdisclosed herein.

FIG. 1 is a schematic functional block diagram showing an example of abasic configuration of a range imaging system according to BasicConfiguration in Embodiments.

FIG. 2A is a planar structure diagram showing an example of aconfiguration of a solid-state imaging device (an image sensor) includedin the range imaging system according to Basic Configuration inEmbodiments.

FIG. 2B is a planar structure diagram showing a specific example of thesolid-state imaging device shown in FIG. 2A.

FIG. 2C is a planar structure diagram showing a modification example ofthe solid-state imaging device shown in FIG. 2A.

FIG. 3 is a timing chart showing an example of operations of a lightemission signal and an exposure signal according to Basic Configurationin Embodiments.

FIG. 4 is a functional block diagram showing a schematic configurationexample of a range imaging system according to Embodiment 1.

FIG. 5 is a timing chart showing an example of operations of a lightemission signal and an exposure signal according to Embodiment 1.

FIG. 6 is a schematic mounting diagram showing a first mounting exampleof the range imaging system according to Embodiment 1.

FIG. 7 is a schematic mounting diagram showing a second mounting exampleof the range imaging system according to Embodiment 1.

FIG. 8 is a diagram showing an example of an operation in the secondmounting example of the range imaging system according to Embodiment 1.

FIG. 9 is a schematic mounting diagram showing a third mounting exampleof the range imaging system according to Embodiment 1.

FIG. 10 is a functional block diagram showing a schematic configurationexample of a range imaging system according to Embodiment 2.

FIG. 11 is a diagram showing an example of a displayed image on adisplay unit when the range imaging system according to Embodiment 2 ismounted to transportation equipment (a vehicle).

FIG. 12 is a diagram showing a mounting example in which the rangeimaging system according to Embodiment 2 is mounted to a vehicle, aswell as showing an example of a displayed image on the display unit.

FIG. 13A is an explanatory diagram showing an example of a displayedimage on the display unit according to Embodiment 2.

FIG. 13B is an explanatory diagram showing another example of adisplayed image on the display unit according to Embodiment 2.

FIG. 14 is a functional block diagram showing a schematic configurationexample of a range imaging system according to Embodiment 3.

FIG. 15 is a diagram showing a mounting example in which the rangeimaging system according to Embodiment 3 is mounted to a vehicle, aswell as showing an example of a displayed image on a display unit.

FIG. 16 is a functional block diagram showing a schematic configurationexample of a range imaging system according to Embodiment 4.

FIG. 17A is a diagram showing an example of a normally captured imagewhen the range imaging system according to Embodiment 4 is mounted to avehicle.

FIG. 17B is a diagram showing an example of a wide angle image when therange imaging system according to Embodiment 4 is mounted to a vehicle.

FIG. 18A is a diagram showing an example of an image captured in thedaytime when the range imaging system according to Embodiment 4 ismounted to a vehicle.

FIG. 18B is a diagram showing an example of an image captured in thelate afternoon or nighttime when the range imaging system according toEmbodiment 4 is mounted to a vehicle.

FIG. 19 is a functional block diagram showing a schematic configurationexample of a range imaging system according to Embodiment 5.

FIG. 20 is a functional block diagram showing a schematic configurationexample of a range imaging system according to Embodiment 6.

FIG. 21 is a detailed structure diagram showing an example in which apulsed-light source unit having a diffraction grating according toEmbodiment 6 is applied to the range imaging system shown in FIG. 10.

FIG. 22 is a schematic diagram showing an example in which the rangeimaging system shown in FIG. 20 or FIG. 21 according to Embodiment 6 ismounted to a vehicle (transportation equipment).

FIG. 23 is a diagram showing an example of screen display of a displayunit according to Embodiment 6.

FIG. 24A is a diagram showing an example of arrangement of irradiationpoints of a plurality of irradiation active light beams according toEmbodiment 6.

FIG. 24B is a diagram showing an example of arrangement of irradiationpoints of a plurality of irradiation active light beams as well asshowing a subject, according to Embodiment 6.

FIG. 25A is a diagram showing another example of arrangement of linearirradiation points of a plurality of irradiation active light beamsaccording to Embodiment 6.

FIG. 25B is a diagram showing another example of arrangement of linearirradiation points of a plurality of irradiation active light beams aswell as showing target subjects, according to Embodiment 6.

FIG. 26A is a diagram showing an example of a pulsed-light source unitthat changes the arrangement of irradiation points or the shape of alaser light beam, according to Embodiment 6.

FIG. 26B is a diagram showing another example of the pulsed-light sourceunit that changes the arrangement of irradiation points or the shape ofa laser light beam, according to Embodiment 6.

FIG. 27 is a functional block diagram showing a schematic configurationexample of a range imaging system according to Embodiment 6.

FIG. 28 is a timing chart of a light emission signal and a plurality ofirradiation active light beams in a typical system.

FIG. 29 is a timing chart of the light emission signal and the pluralityof irradiation active light beams at inconstant periodic timingsaccording to Embodiment 6.

FIG. 30 is a timing chart of the light emission signal and the pluralityof irradiation active light beams at unique timings according toEmbodiment 6.

FIG. 31 is an explanatory diagram showing an example in which sourcelight is divided into a plurality of irradiation active light beams by adiffraction grating, according to Embodiment 6.

FIG. 32 is a functional block diagram showing a schematic configurationof a conventional ranging system.

DESCRIPTION OF EMBODIMENTS

The following describes a range imaging system according to embodimentsof the present disclosure, with reference to the drawings. Each of theexemplary embodiments described below shows a general or specificexample. Therefore, the numerical values, shapes, materials, structuralelements, the arrangement and connection of the structural elements, andso forth shown in the exemplary embodiments below are mere examples, andtherefore do not limit the present disclosure.

Note also that range imaging systems according to Embodiments 1 to 5described below can be used in combination.

Basic Configuration in Embodiments

FIG. 1 is a schematic functional block diagram showing an example of abasic configuration of a range imaging system 10 according to BasicConfiguration in Embodiments.

As shown in FIG. 1, the range imaging system 10 includes an imaging unit30, a pulsed-light source unit 20, a control unit 60, and a calculationunit 50.

The pulsed-light source unit 20 performs light irradiation for rangingof a subject, according to timing of receiving a light emission signalgenerated by the control unit 60. The pulsed-light source unit 20, whichhas a drive circuit, a capacitor, and a light emitting element, emitspulsed light (hereinafter, referred to as the irradiation active light)by supplying electrical charge held by the capacitor to the lightemitting element. As an example, the irradiation active light isinfrared light (IR light) including near-infrared light. Various kindsof light emitting elements, such as a laser diode and a light emittingdiode (LED), can be used as the light emitting element.

The light emitting element does not have to be a single-color lightemitting element. For example, irradiation may be selectively performedby the light emitting element that emits visible light (near-infraredlight, for instance). To be more specific, a combination of lightemitting elements that emit light of different colors, such as a redlight emitting element, a blue light emitting element, and a yellowlight emitting element, may be used. With this, light selected fromamong wavelength regions of emitted light (such as near-infrared light)can be emitted.

In addition to light dispersed in various directions (that is, typicallight), laser light can be emitted as the irradiation active light.Laser light is superior in directivity and convergence performance andcan keep the generated electromagnetic wavelength constant.

The control unit 60 generates a light emission signal to instruct thepulsed-light source unit 20 to emit the irradiation active light.Moreover, the control unit 60 generates the following signals: anexposure signal to instruct the imaging unit 30 to expose reflectedlight of the irradiation active light (hereinafter, this reflected lightis referred to as the reflected active light); and an exposure signal toexpose subject light, which is usual light caused by outside light suchas sunlight or indoor lighting, in other words, radiant light from thesubject instead of resulting from the irradiation active light(hereinafter, this radiant light is referred to as the passive light).In this way, the control unit 60 has a function as a signal generationunit that generates the light emission signal for instructing lightemission and the exposure signal for instructing exposure.

The imaging unit 30 has a camera lens and a solid-state imaging device40 (an image sensor), and performs exposure and imaging in response tothe exposure signal.

In response to the exposure signal, the solid-state imaging device 40receives the passive light from the subject and outputs an image capturesignal.

Moreover, in response to the exposure signal, the solid-state imagingdevice 40 receives the reflected active light reflected off the subjectirradiated with the irradiation active light emitted from thepulsed-light source unit 20, and outputs an imaging signal.

The calculation unit 50 outputs range information of the subject, on thebasis of both the image capture signal and the imaging signal from theimaging unit 30. More details are described in the followingembodiments.

It should be noted that the following embodiments include an example inwhich the solid-state imaging device 40 has a circuit, such as ananalog-to-digital (A/D) converter, that digitizes the image capturesignal and the imaging signal before outputting these signals.

It should be noted that the following embodiments include an example inwhich some or all of the structural elements included in each of thecontrol unit 60, the imaging unit 30, and the calculation unit 50 areintegrated into a single chip on a semiconductor substrate.

Furthermore, according to the range imaging systems described in thefollowing embodiments, information on a measurable distance is notlimited to a distance to the subject. For example, various distances(dimensions), such as dimensions (including the height and width) of thesubject, can be outputted. More details are described in the followingembodiments.

FIG. 2A is a planar structure diagram showing an example of thesolid-state imaging device 40 according to Basic Configuration inEmbodiments.

As shown in FIG. 2A, the solid-state imaging device 40 includes a pixelfor receiving the passive light (hereinafter, referred to as a firstpixel or a passive pixel) and a pixel for receiving the reflected activelight (hereinafter, referred to as a second pixel or an active pixel).

FIG. 2B is a planar structure diagram showing a specific example of thesolid-state imaging device shown in FIG. 2A. In the example shown inFIG. 2B, each of the passive pixels has a filter that lets through oneof R, G, and B light whereas each of the active pixels has a filter thatlets through IR light. Thus, in the range imaging system 10 includingthe solid-state imaging device 40 shown in FIG. 2B, the pulsed-lightsource unit 20 emits IR light other than visible light and the activepixel receives IR light other than visible light.

FIG. 2C is a planar structure diagram showing a modification example ofthe solid-state imaging device shown in FIG. 2A. In Embodiments, thesolid-state imaging device 40 may include a dual-purpose pixel used asboth the passive pixel and the active pixel as shown in FIG. 2C, insteadof the structure shown in FIG. 2A or FIG. 2B. More specifically, thepassive pixel (the first pixel) may further receive the reflected light(the reflected active light) of the pulsed light (the irradiation activelight). The active pixel (the second pixel) may further receive theradiant light (the passive light) from the subject. The advantages inthis case include, for example, high-sensitivity imaging(high-sensitivity photographing) because of the increased size of alight receiving area (a pixel area) in the solid-state imaging device 40capable of receiving both the passive light and the reflected activelight.

With the corresponding filter for R, G, or B, each of the passive pixelsreceives the passive light. Thus, the R, G, or B pixel outputs an imagecapture signal as a corresponding R, G, or B component. On the otherhand, each of the IR pixels receives the reflected active light andoutputs an imaging signal.

Note that the passive pixel may include an infrared cut filter in thecorresponding R, G, or B filter.

Note also that the R, G, and B filters of the passive pixels may beR+IR, G+IR, and B+IR filters. In this case, infrared light included inthe passive light is received as follows: the R+IR pixel receives an Rcomponent and a part of an infrared component; the G+IR receives a Gcomponent and a part of the infrared component; and the B+IR pixelreceives a B component and a part of the infrared component. Then, eachof these pixels outputs the corresponding image capture signal.

To be more specific, a visible light image can be captured since thepassive pixels receive the passive light, and at the same time, aninfrared light image that can be captured even in, for example, thedarkness can be obtained as well.

The passive pixel may output the image capture signal based on the IRlight.

The passive pixels may not have the respective R, G, and B filters. Insuch a case, a monochrome image can be captured. Alternatively, thepixels may have a structure with which a color image can be capturedwithout the filters (for example, a structure in which the depth of animpurity region of the pixel [photodiode] is changed or the type ordensity of impurities is changed).

The active pixel may have a structure with which the reflected passivelight can be exposed without the filter (for example, a structure inwhich the depth of an impurity region of the pixel [photodiode] ischanged or the type or density of impurities is changed).

Next, FIG. 3 is a timing chart showing an example of operations of thelight emission signal and the exposure signal according to BasicConfiguration in Embodiments. This diagram shows an operation of therange imaging system according to Embodiments, and particularly showstimings at which control signals (the light emission signal and theexposure signal) are transmitted from the control unit 60 to thepulsed-light source unit 20 and the imaging unit 30 (the solid-stateimaging device 40) as well as timings of the reflected active light.

First, the imaging unit 30 (the solid-state imaging device 40) exposesthe passive light in response to the exposure signal during an exposureperiod A shown in FIG. 3. Next, during an exposure period B shown inFIG. 3, the pulsed-light source unit 20 emits the irradiation activelight in response to the light emission signal while the imaging unit 30(the solid-state imaging device 40) exposes the reflected active lightin response to the exposure signal.

The order in which the passive light and the reflected active light areexposed is not limited to the example shown in FIG. 3. For instance,exposures of the passive light and the reflected active light may berepeated.

FIG. 3 shows an example in which the exposure period B starts after apredetermined period of time following the end of the exposure period A.However, the present disclosure is not limited to this, and variousoperation methods can be used. Examples include the following: theexposure period B starts during the exposure period A (that is, theexposure period A and the exposure period B coincide with each other);and the exposure period B starts upon the end of the exposure period A.

Embodiment 1

The following describes a configuration and an operation of a rangeimaging system 10 according to Embodiment 1, with reference to thedrawings. Note that the following mainly describes details ofdifferences from Basic Configuration described thus far.

FIG. 4 is a functional block diagram showing a schematic configurationexample of the range imaging system 10 according to Embodiment 1. FIG. 5is a timing chart showing an example of operations of a light emissionsignal and an exposure signal according to Embodiment 1. This diagramshows an operation of the range imaging system 10 according toEmbodiment 1, and particularly shows timings at which control signalsare transmitted from a control unit 60 to a pulsed-light source unit 20and an imaging unit 30 (a solid-state imaging device 40) as well astimings of reflected active light.

Differences from the basic configuration shown in FIG. 1, FIG. 2A to 2C,and FIG. 3 are mainly explained. The control unit 60 outputs an imagingcontrol signal to the imaging unit 30 (an imaging control unit 35) and acalculation unit 50. This imaging control signal is used to controloptical magnification or electronic magnification via, for example, theimaging control unit 35 in the imaging unit 30 to cause a display unit70 to display an image of a target part of a subject to be measured withpassive light. More specifically, an operation of the imaging controlunit 35 includes, as an example, controlling an optical component, suchas a zoom lens of a camera. Note that this dimensional measurement ofthe subject is described later.

The imaging unit 30 outputs an image capture signal obtained bycapturing an image of the subject during an exposure period A shown inFIG. 5.

Moreover, the imaging unit 30 performs exposure (light reception)multiple times on a region including a target object (the subject),according to timings indicated by the exposure signals generated by thecontrol unit 60 (a signal generation unit). Then, during an exposureperiod B shown in FIG. 5, the imaging unit 30 outputs a time-of-flight(TOF) signal, which is a range signal corresponding to a total amount ofmultiple exposures, as an imaging signal.

Next, the following describes details of an operation method and rangecalculation of the range imaging system 10 according to Embodiment 1.The range imaging system 10 can measure a distance to the subject aswell as the dimensions of the subject, such as the height and width ofthe subject.

First, the details of the measurement and calculation of the distance tothe subject are described, with reference to FIG. 5. Here, the basicprinciple is presented by a TOF method by which a distance is measuredfrom a period of time taken for projected light to travel to ameasurement target and back. The reflected active light from themeasurement target (the subject) is exposed by the active pixels in thesolid-state imaging device 40 in two patterns, i.e., at two differenttimings with a first exposure signal and a second exposure signal as theexposure signals in response to the light emission signal. Then, thedistance to the measurement target is calculated on the basis of a ratioof the amounts of light by the exposures. To be more specific, exposureis performed on the subject multiple times according to the timingsindicated by the exposure signals generated by the control unit 60, andthe imaging signal corresponding to a total amount of multiple exposuresis outputted.

For example, the first exposure signal causes the reflected light fromthe measurement target to be fully covered by exposure. Moreover, thesecond exposure signal causes the amount of exposure to increase with adelay of the reflected light of the measurement target from the lightemission timing. To detect an offset component, such as backgroundlight, the light emission signal is stopped and exposure is performedunder the same conditions as those of the first and second exposuresignals.

Then, a distance L to the subject is calculated using Expression 1below. In Expression 1, S1 represents a total amount of exposure by thefirst exposure signal, S0 represents a total amount of exposure by thesecond exposure signal, BG represents a total amount of exposure forbackground light, T0 represents a duration of the light emission signalof direct light to be emitted, and c represents a light speed.Hereinafter, this range calculation is referred to as the TOF rangecalculation.

$\begin{matrix}{L = {\frac{c \cdot T_{0}}{2} \times \left( \frac{{S\; 1} - {BG}}{{S\; 0} - {BG}} \right)}} & {{Expression}\mspace{14mu} 1}\end{matrix}$

The timings of the light emission signal, the first exposure signal, andthe second exposure signal for one screen may be as follows. The lightemission signal and the first exposure signal are outputted multipletimes. Following this, the light emission signal and the second exposuresignal are outputted the same multiple times. Then, after this, thelight emission signal is stopped in order for the exposure signals to beoutputted the same multiple times under the same conditions as those ofthe first and second exposure signals. With this sequence of timingsbeing one set, multiple sets of signal output may be performed. Then,with the output of the accumulated amount of exposure, the distance tothe subject may be calculated by Expression 1.

The range imaging system 10 according to Embodiment 1 may use adifferent method other than the aforementioned TOF method. Examples ofsuch a method include a pattern irradiation method by which rangecalculation is performed using a distortion caused in the reflectedactive light obtained by the application of irradiation active light tothe subject.

Next, details on the measurement and calculation of the dimensions ofsubject are described.

First, the solid-state imaging device 40 receiving the passive lightcaptures an image of the subject according to the exposure signal fromthe control unit 60, and outputs an image signal (image capture signal)to the calculation unit 50.

The calculation unit 50 detects the subject on which the dimensionalmeasurement is to be performed, and calculates a first subject dimensionfrom, for example, a displayed dimension on the display unit 70 andinitial values stored (or recorded) in the range imaging system 10.

Next, a dimension of the subject, such as the height or width, iscalculated using the calculated first subject dimension and the distanceto the subject that is calculated by the aforementioned TOF rangecalculation (while calculation correction is performed using theaforementioned image magnification coefficient [the imaging controlsignal] in some cases).

In this way, the range imaging system 10 according to Embodiment 1 canmeasure the distance to the subject as well as various distances(dimensions) of the subject (such as the height and width of thesubject).

Moreover, according to the range imaging system 10 in Embodiment 1, theimage signal (image capture signal) and the TOF signal (imaging signal)are outputted from the same device, that is, the solid-state imagingdevice 40. In other words, the imaging signals from the solid-stateimaging device 40, which is a single-plate device, have the same imagingcenter (optical center or optical axis center). On this account, a phasedifference between the imaging signals is small and thus the imagingsignals are synchronized more accurately, for example. Hence, thedimensions of the subject can be measured accurately.

Here, even when including a plurality of solid-state imaging devices(that is, even when the imaging unit 30 is a stereo camera), the rangeimaging system 10 according to Embodiment 1 can measure the distance tothe subject as well as the dimensions of the subject, such as the heightand width.

Next, a mounting example of the range imaging system 10 according toEmbodiment 1 is described.

FIG. 6 is a schematic mounting diagram showing a first mounting exampleof the range imaging system 10 shown in FIG. 4. FIG. 6 is a diagramshowing an example in which the range imaging system 10 is mounted to asmartphone (portable communication terminal) as an example of portableequipment.

In the example shown in FIG. 6, pointing this smartphone at an animal(subject) to display the subject on a display unit 70 of the smartphoneenables the dimensions (such as the height and width) of the subject tobe measured (ranged). To be more specific, the dimensions (such as theheight and width) of the subject can be measured (ranged) by theaforementioned calculation performed by the calculation unit 50 usingthe following signals: the image signal (image capture signal) outputtedfrom the solid-state imaging device 40 (the passive pixels) receivingthe passive light; and the TOF signal (image signal) outputted from thesolid-state imaging device 40 (the active pixels) receiving thereflected active light of the irradiation active light emitted from thepulsed-light source unit 20.

It is more preferable that the range information on the dimensions (suchas the height and width) of the subject is stored in association withthe passive signal (i.e., the image) obtained by imaging the subjectwith the passive light. With this, when the stored image is to bedisplayed on the display unit again, various kinds of dimensionalinformation on the subject can be checked again by designating a desiredpart of the subject.

It is more preferable that the irradiation active light emitted from thepulsed-light source unit 20 is laser light in the mounting example shownin FIG. 6 as well as when more emphasis is placed on, for example,miniaturization of the range imaging system 10, reduction of themeasurement time, and low power consumption.

More specifically, the subject can be irradiated with the irradiationactive light using the laser light in the pinpoint accuracy, and thusthe distance to the subject can be measured by means of the reflectedactive light from one point (partial region) on the subject. Then, thedimensions (such as the height and width) of the subject can be measuredusing this range information.

Thus, the imaging speed of the solid-state imaging device 40 isincreased and the amount of signal is reduced. This can achieve, forexample, miniaturization of the system, reduction of the measurementtime, and low power consumption. Moreover, since the imaging signalrepresents signal information entirely from the subject, noisecomponents in the imaging signal can be reduced. Therefore, thedimensions of the subject can be measured with high accuracy.

In the case where the pulsed-light source unit 20 emits laser light, thedisplay unit 70 may display which part of the subject is irradiated withthe irradiation active light (laser light). In the example of screendisplay shown in FIG. 6, a mark indicating an irradiation point on thesubject irradiated with the irradiation active light is displayed. Inaddition, the dimension (such as the height or width) of the subject maybe displayed on the display unit 70 as shown in FIG. 6.

Furthermore, in the case where the pulsed-light source unit 20 emitslaser light, a visual laser light source, which is synchronized with thepulsed-light source unit 20 and has the optical axis appropriatelyadjusted, may be included. With this visual laser light source, whichpart of the subject is irradiated with the pulsed light can be checkedeasily and visually, for example. Thus, the subject may be irradiatedwith both the irradiation active light (laser light) and the visuallaser light. In other words, the range imaging system 10 may includeanother light source that emits light (visual laser light, as anexample) synchronizing with the pulsed light.

FIG. 7 is a schematic mounting diagram showing a second mounting exampleof the range imaging system 10 shown in FIG. 4. FIG. 7 is a diagramshowing another example in which the range imaging system 10 is mountedto a smartphone (portable communication terminal) as an example ofportable equipment.

The example shown in FIG. 7 is different from the example shown in FIG.6 in that the pulsed-light source unit 20 in FIG. 7 is equipped with aline lens that enables the irradiation active light to be emitted aslinear light to the subject. To be more specific, an irradiation regionof the line lens has a linear shape or a long narrow strip shape. In theexample of screen display in FIG. 7, an alternate long and short dashline indicates the irradiation region.

Capturing an image of the subject by irradiating the whole subject withthis straight light sequentially like scanning allows three-dimensionaldimensions of the subject to be measured (ranged) with high accuracy andat high speed. Then, the data based on the three-dimensional dimensionscan be outputted using a three-dimensional printer (hereinafter,referred to as a 3D printer) with high accuracy and at high speed.

To output the data using the 3D printer, an enormous amount of data istypically required, and a long calculation and output time is alsorequired. However, with the range imaging system 10 according toEmbodiment 1, the calculation time and the output time can be reduced,during which both the calculation and the output are performed at highaccuracy. This reduction in time enables the data output using the 3Dprinter to be performed speedily and easily.

FIG. 8 is a diagram showing an example of an operation in the secondmounting example. In the case where the image of the whole subject issequentially captured (or, scanned) as shown in FIG. 8, a display unitof the portable equipment may display the scanned part by adding achange in the image (as an example, the scanned part may be colored) onthe display unit. Such display can make it easy to check the scanningand also can improve the scanning accuracy. In the example of screendisplay in FIG. 8, an alternate long and short dash line indicates theirradiation region and a shaded region indicates the scanned part.

FIG. 9 is a schematic mounting diagram showing a third mounting exampleof the range imaging system 10 shown in FIG. 4. FIG. 9 is a diagramshowing an example in which the range imaging system 10 is mounted to avehicle (transportation equipment).

In FIG. 9, the pulsed-light source unit 20 is placed in a front grilleand the imaging unit 30 is placed in an upper interior (near a rearviewmirror) of the vehicle.

The placement of the range imaging system 10 is not limited to theabove. For example, the pulsed-light source unit 20 may be placed in aheadlight or a fog lamp, and the imaging unit 30 may be placed in afront grille or a front bumper.

Subjects in FIG. 9 include a road under an elevated structure, oralternatively called a tunnel (hereinafter, collectively referred to asthe tunnel), which can be an obstacle. Assume that the vehicle is goingto drive through this tunnel.

In this case, the range imaging system 10 according to Embodiment 1mounted to the vehicle measures a distance to the tunnel as well as thedimensions (such as the height and width) of the tunnel using thefollowing signals: the image signal (image capture signal) outputtedfrom the solid-state imaging device 40 (the passive pixels) receivingthe passive light; and the TOF signal (image signal) outputted from thesolid-state imaging device 40 (the active pixels) receiving thereflected active light.

With this, a driver of this vehicle can find the distance to the tunnelthat can be an obstacle. Moreover, the driver can also determine, forexample, whether the vehicle of the driver can drive through the tunnel(the subject).

Furthermore, the dimensions of the vehicle or the like may be previouslystored (or recorded) as initial values (as initial information, storedinformation, or recorded information) into the system. With this, whenthe system determines that it is difficult for the vehicle to drivethrough the obstacle, in addition to when the vehicle approaches theobstacle (the subject), an issue of an alarm or the like, automaticspeed control, or automatic stop can be executed for example. Hence, arisk can be avoided more easily.

Although the range imaging system 10 according to Embodiment 1 ismounted for the purpose of making a measurement in front of the vehiclein FIG. 9, the purpose is not limited to this. For example, the rangeimaging system 10 may be placed near the license plate at the back ofthe vehicle to make a measurement behind the vehicle. Alternatively, therange imaging system 10 may also be placed on, for example, a sideviewmirror to make a measurement on the side of the vehicle.

Although the range imaging system 10 according to Embodiment 1 has beendescribed with reference to FIG. 7 to FIG. 9, the mounting example isnot limited to the above in which the range imaging system 10 is mountedto the portable equipment and the vehicle. For example, the rangeimaging system 10 can be mounted to various kinds of equipment andfacilities including the following: other transportation equipment (suchas a motorcycle, a railroad vehicle, an airplane, and a spacecraft);other portable equipment (such as a notebook personal computer [PC], atablet PC, portable information equipment, and a portable communicationterminal); transportation equipment; infrastructure equipment; heavyequipment (such as a power shovel and a bulldozer); and householdequipment.

Embodiment 2

The following describes a configuration and an operation of a rangeimaging system 10 according to Embodiment 2, with reference to thedrawings. Note that the following mainly describes details ofdifferences from Basic Configuration and from the embodiment describedabove.

FIG. 10 is a functional block diagram showing a schematic configurationexample of the range imaging system 10 according to Embodiment 2.

Differences from the basic configuration shown in FIG. 1, FIG. 2A to 2C,and FIG. 3 and from the configuration shown in FIG. 4 are mainlyexplained. More specifically, the range imaging system 10 according toEmbodiment 2 includes a detection unit 80 that detects a specificsubject, which is to be a ranging target, in the whole subject sceneobtained from a passive image signal. On the basis of the detectionresult, the detection unit 80 instructs a control unit 60 to issue alight emission instruction to a pulsed-light source unit 20.

To be more specific, the detection unit 80 issues a signal forirradiating the subject with the irradiation active light. Receivingthis signal, the control unit 60 changes an irradiation direction of theirradiation active light to cause a light-source moving unit 25 in thepulsed-light source unit 20 to irradiate the specific subject with thelight. To change the irradiation direction of the irradiation activelight, the detection unit 80 may input the signal directly to thepulsed-light source unit 20.

It should be noted that Embodiment 2 includes an example in which someor all of the structural elements included in each of the control unit60, an imaging unit 30, the detection unit 80, and a calculation unit 50are integrated into a single chip on a semiconductor substrate.

Next, the following describes details of range calculation of the rangeimaging system 10 according to Embodiment 2.

First, the detection unit 80 detects a subject that requires rangingfrom a whole subject scene, using a passive image signal outputted froma solid-state imaging device 40 (passive pixels) receiving passivelight. The number of subjects does not need to be one and thus may bemore than one.

Next, from detection information on a location of the subject, thedetection unit 80 outputs a signal for specifying the direction in whichthe pulsed-light source unit 20 emits the pulsed light (this signal isreferred to as the light-source moving instruction signal) to thepulsed-light source unit 20 (the light-source moving unit 25 in thepulsed-light source unit 20) via the control unit 60. The detection unit80 may output this light-source moving instruction signal directly tothe pulsed-light source unit 20 (the light-source moving unit 25 in thepulsed-light source unit 20) by bypassing the control unit 60.

The pulsed-light source unit 20 irradiates the subject with theirradiation active light. Then, the solid-state imaging device 40 (theactive pixels) receives (exposes) the resulting reflected active light,and outputs the TOF signal to the calculation unit 50.

The calculation unit 50 measures (ranges) a distance to the subjectusing the TOF signal, by the TOF range calculation described above inEmbodiment 1.

With the range imaging system 10 according to Embodiment 2 describedthus far, the subject subjected to the ranging is detected and the TOFsignal is thus outputted, resulting in a reduction in noise components.Hence, the distance to the subject can be measured with high accuracyand at high speed.

FIG. 11 is a diagram showing an example of a displayed image on adisplay unit 70 when the range imaging system 10 shown in FIG. 10 ismounted to a vehicle (transportation equipment). In FIG. 11, a scene infront of the vehicle is displayed.

As shown in FIG. 11, a person and an animal crossing a street (roadway)in a traffic lane as well as different kinds of street trees aredisplayed as a whole subject scene. Note that one of the street trees islocated closer to the vehicle than the person and the animal.

The range imaging system 10 according to Embodiment 2 stores (orrecords) initial information on the subject, i.e., the specific subject,which has a higher priority to be ranged. The range imaging system 10detects in particular, for example, a person, an animal, or a physicalobject in the street as the specific subject to be ranged by priority.More specifically, the range imaging system 10 detects such a specificsubject from the whole subject scene.

Thus, the imaging time taken by the solid-state imaging device 40 forthe reflected active light is reduced and the amount of signal is alsoreduced. This can achieve, for example, miniaturization of the system,reduction of the measurement time, and low power consumption. Moreover,since the imaging signal represents signal information from the subject(the specific subject), noise components in the imaging signal can bereduced. Therefore, the dimensions of the subject (the specific subject)can be measured with high accuracy.

FIG. 12 is a diagram showing a mounting example in which the rangeimaging system 10 shown in FIG. 10 is mounted to a vehicle(transportation equipment), as well as showing an example of a displayedimage on the display unit 70. The display unit 70 in FIG. 12 displays ascene in front of the vehicle.

A preceding vehicle and a street tree are displayed as subjects. Therange imaging system 10 according to Embodiment 2 stores (or records)initial information on the subject having a higher priority to beranged. Thus, the range imaging system 10 detects the preceding vehicleby priority. More specifically, the range imaging system 10 detects thesubject (the specific subject) from the whole subject scene.

In addition to measuring the distance to the preceding vehicle (thesubject), drive control of the vehicle (such as an issue of an alarm orthe like, automatic speed control, or automatic stop) may be executed.Such measurement and drive control enables safer driving.

Each of the passive pixels of the solid-state imaging device 40according to Embodiment 2 outputs an image capture signal as acorresponding R, G, or B component. In other words, the passive pixelsoutput a colored image. On this account, the specific subject can bedetected from the whole subject scene not only by its shape but also bya different detection reference.

FIG. 13A and FIG. 13B are explanatory diagrams, each showing an exampleof a displayed image on the display unit 70. As shown in FIG. 13A andFIG. 13B, colors are used as an example of the different detectionreference. For example, a traffic light in FIG. 13A is green (a go-aheadindication) and thus may not to be detected as the subject (or, thepriority is lowered more than the other subjects). When a traffic lightis yellow (a caution indication) or red (a stop indication) as shown inFIG. 13B, the traffic light may be detected as the subject. In this way,advanced detection can be achieved.

It is more preferable that the irradiation active light emitted from thepulsed-light source unit 20 is laser light in the mounting example shownin FIG. 12 as well as when more emphasis is placed on, for example,miniaturization of the range imaging system 10, reduction of themeasurement time, and low power consumption.

Although the range imaging system 10 according to Embodiment 2 ismounted for the purpose of making a measurement in front of the vehiclein FIG. 12, the purpose is not limited to this. For example, the rangeimaging system 10 may be placed near the license plate at the back ofthe vehicle to make a measurement behind the vehicle. Alternatively, therange imaging system 10 may also be placed on, for example, a sideviewmirror to make a measurement on the side of the vehicle.

Although the range imaging system 10 according to Embodiment 2 ismounted for the purpose of making a measurement in front of and outsidethe vehicle (the system-mounted equipment) in FIG. 12, the purpose isnot limited to this. For example, the range imaging system 10 accordingto Embodiment 2 may be placed inside the vehicle. For instance, a humanhead may be detected as a subject, and movement (wobble) of the humanhead may be measured as range information. Such detection andmeasurement enables the system inside the vehicle to be used to detect,for example, a drowsy driver.

Although the range imaging system 10 according to Embodiment 2 has beendescribed with reference to FIG. 12, the mounting example is not limitedto the above in which the range imaging system 10 is mounted to thevehicle. For example, the range imaging system 10 can be mounted tovarious kinds of equipment and facilities including the following: othertransportation equipment (such as a motorcycle, a railroad vehicle, anairplane, and a spacecraft); portable equipment (such as a smartphone, anotebook PC, a tablet PC, portable information equipment, and a portablecommunication terminal); transportation equipment; infrastructureequipment; heavy equipment (such as a power shovel and a bulldozer); andhousehold equipment.

Embodiment 3

The following describes a configuration and an operation of a rangeimaging system 10 according to Embodiment 3, with reference to thedrawings. Note that the following mainly describes details ofdifferences from Basic Configuration and from the embodiments describedabove.

FIG. 14 is a functional block diagram showing a schematic configurationexample of the range imaging system 10 according to Embodiment 3. Thisrange imaging system 10 has both functions described in Embodiments 1and 2. To be more specific, the range imaging system 10 according toEmbodiment 3 can measure the dimensions of a subject with higheraccuracy and at a higher speed as well as measuring a distance to thesubject.

FIG. 15 is a diagram showing a mounting example in which the rangeimaging system 10 shown in FIG. 14 is mounted to a vehicle, as well asshowing an example of a displayed image on a display unit 70. In FIG.15, a scene in front of the vehicle is displayed as an example of thedisplayed image. Subjects in FIG. 15 include a tunnel and a street treelocated near the tunnel. Assume that the vehicle is going to drivethrough this tunnel.

Next, the following describes details of range calculation of the rangeimaging system 10 according to Embodiment 3, with reference to FIG. 14and FIG. 15.

First, a detection unit 80 determines a subject that requires rangingfrom a whole subject scene, using a passive image signal outputted froma solid-state imaging device 40 (passive pixels) receiving passivelight. To be more specific, an image capture signal is outputted fromthe solid-state imaging device 40 (the passive pixels) that receives thepassive light from the subjects to capture an image of (perform imagingon) the whole subject scene including the tunnel and the street tree.Receiving this image capture signal, the detection unit 80 detects thesubject.

The range imaging system 10 according to Embodiment 3 stores (orrecords) initial information on, for example, a type of the subjectwhich has a higher priority to be ranged. When used for automotiveapplication, the range imaging system 10 according to Embodiment 3detects in particular, for example, a preceding vehicle (such as anautomobile, a motorcycle, an electric cycle bicycle, or a bicycle), aperson, an animal, or a physical object in the street as the subject tobe ranged by priority. More specifically, the range imaging system 10detects such a subject from the whole subject scene.

In FIG. 15, the tunnel is detected (determined) to have a higherpriority in ranging than the street tree located outside the roadthrough which the vehicle is going drive. However, the subject detectionis not limited to this example. The system may store (or record) variouskinds of initial information, which enables the system to effectivelydetect the subject with higher accuracy.

Next, having the information on a location of the subject, the detectionunit 80 outputs a signal for specifying the direction in which apulsed-light source unit 20 emits the pulsed light (this signal isreferred to as the light-source moving instruction signal) to thepulsed-light source unit 20 (a light-source moving unit 25 in thepulsed-light source unit 20) via a control unit 60. The detection unit80 may output this light-source moving instruction signal directly tothe pulsed-light source unit 20 (the light-source moving unit 25 in thepulsed-light source unit 20) by bypassing the control unit 60.

The pulsed-light source unit 20 irradiates the subject with the pulsedlight. Then, the solid-state imaging device 40 (the active pixels)exposes the resulting reflected active light, and outputs a TOF signalto the calculation unit 50.

The calculation unit 50 measures (ranges) a distance to the subjectusing the TOF signal, by the TOF range calculation described above inEmbodiment 1.

Moreover, the calculation unit 50 detects the subject on which thedimensional measurement is to be performed, and calculates a firstsubject dimension from, for example, a displayed dimension on thedisplay unit 70 and initial values stored (or recorded) in the rangeimaging system 10. Then, using the calculated first subject dimensionand the distance to the subject calculated by the aforementioned TOFrange calculation, a dimension of the subject such as the height orwidth is calculated while, in some cases, calculation correction isperformed using the aforementioned image magnification coefficient (theimaging control signal).

By the calculation described above, the range imaging system 10according to Embodiment 3 can measure the distance to the subject aswell as the dimensions of the subject, such as the height and width.

Since a subject having a lower priority is not subjected to ranging inEmbodiment 3, the measurement time can be reduced. Moreover, a signal tobe possibly a noise component in the ranging of the subject (such asimaging and range information on the street tree shown in FIG. 15) canbe reduced. Hence, multiple distances (dimensions) of the subject can bemeasured with higher precision.

Although the range imaging system 10 according to Embodiment 3 ismounted for the purpose of making a measurement in front of the vehiclein FIG. 15, the purpose is not limited to this. For example, the rangeimaging system 10 may be placed near the license plate at the back ofthe vehicle to make a measurement behind the vehicle. Alternatively, therange imaging system 10 may also be placed on, for example, a sideviewmirror to make a measurement on the side of the vehicle.

Although the range imaging system 10 according to Embodiment 3 ismounted for the purpose of making a measurement in front of and outsidethe vehicle (the system-mounted equipment) in FIG. 15, the purpose isnot limited to this. For example, the range imaging system 10 accordingto Embodiment 3 may be placed inside the vehicle. For instance, a humanhead may be detected as a subject, and movement (wobble) of the humanhead may be measured as range information. Such detection andmeasurement enables the system inside the vehicle to be used to detect,for example, a drowsy driver.

Although the range imaging system 10 according to Embodiment 3 has beendescribed with reference to FIG. 15, the mounting example is not limitedto the above in which the range imaging system 10 is mounted to thevehicle. For example, the range imaging system 10 can be mounted tovarious kinds of equipment and facilities including the following: othertransportation equipment (such as a motorcycle, a railroad vehicle, anairplane, and a spacecraft); portable equipment (such as a smartphone, anotebook PC, a tablet PC, portable information equipment, and a portablecommunication terminal); transportation equipment; infrastructureequipment; heavy equipment (such as a power shovel and a bulldozer); andhousehold equipment.

Embodiment 4

The following describes a configuration and an operation of a rangeimaging system 10 according to Embodiment 4, with reference to thedrawings. Note that the following mainly describes details ofdifferences from Basic Configuration and from the embodiments describedabove.

FIG. 16 is a functional block diagram showing a schematic configurationexample of the range imaging system 10 according to Embodiment 4.

First, the range imaging system 10 according to Embodiment 4 performsrange calculation directly using an image capture signal (hereinafter,referred to as the image range calculation).

An example of the image range calculation is as follows. A solid-stateimaging device 40 (passive pixels) of an imaging unit 30 captures animage sequence and outputs a signal of the image sequence (an imagecapture signal) to a calculation unit 50. Then, the calculation unit 50compares a current frame (image) with a preceding frame (image) toderive a distance by calculation.

Under a ranging environment satisfying a predetermined condition in, forexample, automotive application (application to transportationequipment), an inter-vehicular distance to a preceding vehicle can bemeasured every moment by this image range calculation method. Then, alarge change in the distance between the frames stored (or recoded) asvideo is determined to be a sudden approach to the preceding vehicle.Thus, this image range calculation method has the advantage of makingsuch a determination relatively easily. More specifically, the methodhas the advantage of measuring the distance to the preceding vehiclewith a small amount of calculation.

On the other hand, under a ranging environment not satisfying thecondition, the image range calculation method has the disadvantage thatthe ranging accuracy is significantly reduced (or, that ranging cannotbe performed at all). Thus, the range imaging system 10 according toEmbodiment 4 is to solve this disadvantage.

The following describes details of the range imaging system 10 accordingto Embodiment 4 with reference to FIG. 16.

First, a detection unit 80 detects a state of the ranging environment onthe basis of a passive image signal outputted from the solid-stateimaging device 40 and determines whether the state of the rangingenvironment satisfies the condition for performing the image rangecalculation. The details on this determination are described later.

When determining that the state of the ranging environment does notsatisfy the condition for performing the image range calculation andthat ranging by the image range calculation is difficult, the detectionunit 80 issues an instruction signal to a control unit 60 for TOF rangecalculation.

Receiving the instruction signal from the control unit 60, apulsed-light source unit 20 irradiates a subject with the pulsed light.Then, the solid-state imaging device 40 (the passive pixels) exposes theresulting reflected active light, and outputs a TOF signal to thecalculation unit 50.

Moreover, the detection unit 80 outputs an image control signal to thecalculation unit 50. Receiving this instruction signal, the calculationunit 50 measures (ranges) a distance to the subject by the TOF rangecalculation.

Next, the following describes an example of a condition in which therange imaging system 10 according to Embodiment 4 determines thatranging by the image range calculation is difficult and thus switchesthe range calculation method.

FIG. 17A and FIG. 17B are diagrams, each showing an example of an imagecaptured according to a passive signal from the solid-state imagingdevice 40 (the passive pixels) in the case where the range imagingsystem 10 according to Embodiment 4 is mounted to a vehicle. FIG. 17Ashows an example of a normally captured image whereas FIG. 17B shows anexample of a wide-angle captured image.

As apparent from FIG. 17B, wide-angle image capture enables imaging of awider region even when a distance to a subject is short. However,subject distortion occurs to a peripheral region (Region A in FIG. 17B)of a wide-angle captured image.

To be more specific, the subject (obstacle) in FIG. 17A is captured withno image distortion. On the other hand, although the obstacle in FIG.17B can be recognized, the data including a large distortion make itdifficult to measure the distance to the obstacle accurately.

In the case of the image range calculation performed using theaforementioned sequential image capture (the image sequence) inparticular, distortion between the images is rendered more excessively.Thus, the error increases in the image range calculation, thereby makingit difficult to measure the distance.

With this being the situation, when the subject in Region A of FIG. 17Bis subjected to ranging, the TOF range calculation is performed.According to the range imaging system 10 in Embodiment 4, the imagesignal (image capture signal) and the TOF signal (imaging signal) areoutputted from the same device, that is, the solid-state imaging device40. In other words, the imaging signals from the solid-state imagingdevice 40, which is a single-plate device, have the same imaging center(optical center or optical axis center). On this account, a phasedifference between the imaging signals is small and thus the imagingsignals are synchronized more accurately, for example. Hence, with thehigh compatibility and high correlativity between the range calculationresult (range information) by the image range calculation and thecalculation result (range information) by the TOF range calculation,ranging can be performed with higher accuracy.

Here, even when including a plurality of solid-state imaging devices(that is, even when the imaging unit 30 is a stereo camera), the rangeimaging system 10 according to Embodiment 4 can switch the calculationmethod between the image range calculation and the TOF rangecalculation.

Moreover, the reason for this selection between the image rangecalculation and the TOF range calculation is not limited to imagedistortion. The selection can be made under other conditions as follows.

A first example is to select between the image capture signal and theimaging signal depending on the time of day or night. FIG. 18A and FIG.18B are diagrams, each showing an example of a captured image obtainedwhen the range imaging system 10 according to Embodiment 4 is mounted toa vehicle. FIG. 18A shows an example of an image captured in the daytimewhereas FIG. 18B shows an example of an image captured in the lateafternoon or nighttime.

In the daytime as shown in FIG. 18A, for example, ranging is performedusing the image range calculation according to Embodiment 4. On theother hand, when a clear image cannot be captured because of, forexample, the nighttime as shown in FIG. 18B, ranging is performed usingthe TOF range calculation. Thus, ranging can be performed with accuracyregardless of any time of day or night.

A second example is to select between the image capture signal and theimaging signal depending on a weather or environmental condition. Forexample, when the system is exposed to the strong afternoon sunshine orthe like or when it rains (that is, when image recognition isdifficult), the TOF range calculation is used. In an environment otherthan this, the image range calculation is used. Thus, ranging can beperformed with high accuracy regardless of any weather or environmentalconditions.

A third example is to select between the image capture signal and theimaging signal depending on a distance to the subject. Morespecifically, the TOF range calculation is used for a short distancethat is likely to result in a wide angle image, and the image rangecalculation is mainly used for a middle or long distance. Thus, rangingcan be performed with high accuracy regardless of any distance to thesubject.

A fourth example is to select between the image capture signal and theimaging signal depending on transportation equipment (such as a vehicle)including the present system or on a motion speed of the subject. It ismore preferable to use the TOF range calculation when, for example, thetransportation equipment moves at high speed, such as 100 km/h or more.

According to Embodiment 4, the image capture signal or the imagingsignal is selected depending on the state of the ranging environment.However, the present disclosure is not limited to this. For example, tomake the calculation result (the ranging result) based on one signalaccurate, the other signal may be used for correction depending on thestate of the ranging environment.

For example, in the fourth example above, when the transportationequipment moves at low speed such as 30 km/h or less, either the resultof the TOF range calculation or the result of the image rangecalculation is used as interpolation information to calculate a finaldistance. Moreover, at medium speed between, for example, 30 km/h and100 km/h, the TOF range calculation or the image range calculation isused depending on an individual frame. Furthermore, at high speed suchas 100 km/h or more, the TOF range calculation is used. Thus, rangingcan be performed with high accuracy regardless of any distance to thesubject.

Embodiment 5

The following describes a configuration and an operation of a rangeimaging system 10 according to Embodiment 5, with reference to thedrawings. Note that the following mainly describes details ofdifferences from Basic Configuration and from the embodiments describedabove.

FIG. 19 is a functional block diagram showing a schematic configurationexample of the range imaging system 10 according to Embodiment 5. As adifference from Embodiment 4 (FIG. 16), the range imaging system 10according to Embodiment 5 does not include a detection unit 80. Instead,an initial value indicating a condition (a selection condition) toswitch between the TOF range calculation and the image range calculationis previously stored (or recorded) in the range imaging system 10. Thus,the range calculation is switched on the basis of an imaging conditionand the initial value.

FIG. 19 shows an example in which the determination is made on the basisof magnification control by reference to the initial value. In the caseof a wide angle imaging, the range calculation is switched according toan image selection signal without detection of a passive signal.

This case does not require a time for detecting the image capture signaland thereby further reduces a time for outputting imaging information ascompared with Embodiment 4. That is, the advantage is that ranging canbe performed in a short time.

Moreover, the reason for this selection between the image rangecalculation and the TOF range calculation is not limited to imagedistortion. The selection can be made under other conditions as follows.

For example, a time of day may be used as the initial value. In such acase, ranging may be performed using the TOF range calculation when itgrows dark around the system. As an example, a time period from 8:00p.m. to 3:00 a.m. may be set as the nighttime. It is preferable that theinitial value for this nighttime is set in more detail according to theseason, such as summer or winter, or according to the geographic region.

Embodiment 6

The following describes a configuration and an operation of a rangeimaging system 10 according to Embodiment 6, with reference to thedrawings. Note that the following mainly describes details ofdifferences from Basic Configuration and from the embodiments describedabove.

FIG. 20 is a functional block diagram showing a schematic configurationexample of the range imaging system 10 according to Embodiment 6.

As a difference from the basic configuration shown in FIG. 1, apulsed-light source unit 20 of the range imaging system 10 according toEmbodiment 6 includes the following: a light source 21 that emits sourcelight (laser light as an example); and a diffraction grating 25 a (alight-source moving unit) that divides the source light into a pluralityof irradiation active light beams (irradiation active light a andirradiation active light b in FIG. 20).

It should be noted that light-source moving performed in thelight-source moving unit shown in FIG. 20 includes the following cases:a case where the light source 21 or the pulsed-light source unit 20itself is moved to change the irradiation direction of the source lightor the irradiation active light; a case where one of light sources 21(light sources 21 a and 21 b shown in FIG. 26B) included in thepulsed-light source unit 20 is selected to change the irradiationdirection of the irradiation active light; a case where the irradiationdirection of the irradiation active light is changed while the sourcelight is being divided by the diffraction grating 25 a; a case where theirradiation direction of the irradiation active light is changed usingthe diffraction grating 25 a and a galvanometer; a case where the lightdivided by the diffraction grating 25 a changes the irradiationdirection of the irradiation active light by means of a reflector (or areflector mounted on a rotating shaft of the galvanometer); a case whereone of the light sources 21 a and 21 b (FIG. 26B) included in thepulsed-light source unit 20 and/or one of the diffraction gratings 25 aand 25 b (FIG. 26A and FIG. 26B) included in the pulsed-light sourceunit 20 is selected to change the irradiation direction of theirradiation active light; and a case where the above cases are combined.Note that the light-source moving is not limited to the above cases.

To facilitate understanding of the present disclosure, the twoirradiation active light beams are shown in FIG. 20. However, the numberof the irradiation active light beams is not limited to this, and thesource light may be divided into a larger number of irradiation activelight beams.

According to the exposure signal, the pulsed-light source unit 20 emitsthe irradiation active light beams, which are then reflected off thesubject. A solid-state imaging device 40 receives a plurality ofresulting reflected active light beams (reflected active light a andreflected active light b in FIG. 20) and outputs an imaging signal.

In FIG. 20, since the source light is laser light, which is superior inrectilinearity, the diffraction grating 25 a can efficiently divide thesource light.

FIG. 21 is a detailed structure diagram showing an example in which thepulsed-light source unit 20 having the diffraction grating 25 a isapplied to the range imaging system 10 shown in FIG. 10. It should benoted that Embodiment 6 can also be applied to the range imaging system10 shown in FIG. 4, FIG. 14, FIG. 16, and FIG. 19.

In FIG. 21, a detection unit 80 firstly detects (specifies) a subjectthat requires ranging from a whole subject scene, using a passive imagesignal outputted from the solid-state imaging device 40 (the passivepixels) receiving passive light.

Next, from detection information on a location of the subject, thedetection unit 80 outputs a light-source moving instruction signal as amovement control signal to the pulsed-light source unit 20 via thecontrol unit 60. This light-source moving instruction signal is used forspecifying the direction in which the pulsed-light source unit 20 emitsthe irradiation active light, the arrangement of irradiation points, orthe shape of the irradiation active light. The detection unit 80 mayoutput the light-source moving instruction signal in place of the movingcontrol signal and the light emission signal shown in FIG. 21, directlyto the pulsed-light source unit 20 by bypassing the control unit 60.

While causing the diffraction grating 25 a (the light-source movingunit) to divide the source light, the pulsed-light source unit 20changes the irradiation direction of the irradiation active light, thearrangement of irradiation points, or the shape of the irradiationactive light. Then, the pulsed-light source unit 20 irradiates thesubject with the irradiation active light beams. The solid-state imagingdevice 40 (the active pixels) receives (exposes) the resulting reflectedactive light beams, and outputs a TOF signal (imaging signal) to thecalculation unit 50.

The calculation unit 50 measures (ranges) a distance to the subjectusing the TOF signal, by the TOF range calculation described above inEmbodiment 1.

It should be noted that a method other than the aforementioned TOFmethod can be used in Embodiment 6 as in the embodiments describedabove. As an example, a pattern irradiation method can be used, by whichthe subject is irradiated with the irradiation active light and thenrange calculation is performed using distortion of the resultingreflected active light. In Embodiment 6 in particular, since theirradiation active light beams are emitted to the plurality ofirradiation points, the pattern irradiation method is especially suitedin addition to the TOF method.

The range imaging system 10 according to Embodiment 6 described thus farhas the following advantages.

A first advantage is that the irradiation active light can reach thesubject located away from the range imaging system 10 withoutattenuating the overall output of the source light (laser light). To bemore specific, as compared with the case where the source light is notdivided using a light source having the same light output as the lightsource 21, a measureable distance (i.e., a distance that the irradiationactive light can reach) can be significantly extended without upsizingthe range imaging system or increasing power consumption.

A second advantage is that the use of the reflected light (the reflectedactive light) from a part of the subject enables the obtainment of anamount of signal sufficient to measure a distance to the subject andalso enables the reduction in the amount of signal for each individualreflected active light beam. Thus, high-speed range calculation (reducedcalculation time) can be achieved.

A third advantage is that an amount of signal sufficient to measure adistance to the subject can be obtained while a signal as a noisecomponent can be reduced. Thus, the accuracy of the distance measurementcan be improved.

Lastly, a fourth advantage is that because of the irradiation by theplurality of irradiation active light beams, the range imaging systemshown 10 in FIG. 21 in particular does not require an extremely highaccuracy to specify the subject (as the image recognition accuracy).Therefore, miniaturization and low cost of the range imaging system, forexample, can be easily achieved.

FIG. 22 is a schematic diagram showing an example in which the rangeimaging system 10 shown in FIG. 20 or FIG. 21 is mounted to a vehicle(transportation equipment). To facilitate understanding of Embodiment 6,FIG. 22 shows that only the irradiation active light a and b reachirradiation points a and b among irradiation points (nine irradiationpoints in FIG. 22) and then resulting reflected active light a and breach the imaging unit 30 (the solid-state imaging device 40). However,in reality, the irradiation active light beams reach all the irradiationpoints and the resulting reflected active light beams reach the imagingunit 30 (the solid-state imaging device 40).

Moreover, the pulsed-light source unit 20 may include a collimating lens22 between the light source 21 and the light-source moving unit (thediffraction grating 25 a), as shown in FIG. 22. Furthermore, the imagingunit 30 may include an imaging lens 41 in front of the solid-stateimaging device 40.

By irradiating the vehicle as well as the buildings behind the vehicleas the subjects with the divided irradiation active light beams as shownin FIG. 22, each of distances to the vehicle and the buildings can bemeasured according to Embodiment 6.

To be more specific, after the detection of the subject (the specificsubject) from the whole subject scene, a region including the subject(the specific subject) is irradiated, as a center region, with theirradiation active light beams. With this, each of the distances to thespecific subject and to the surroundings can be measured.

A display unit 70 according to Embodiment 6 may display where in thesubject the irradiation active light beams from the pulsed-light sourceunit 20 are emitted, as in FIG. 23 showing an example of screen displayof the display unit 70. In this example of screen display in FIG. 23,marks indicating the irradiation points of the irradiation active lightbeams emitted to the subject are displayed.

Moreover, as shown in FIG. 23, the display unit 70 may display each ofthe distances to the irradiation points (indicated by circles in FIG.23). When the distance becomes shorter, the state of the displayeddistance may be changed as follows, for example: the color of thedisplayed distance may be changed; the displayed distance may blink; oran alarm or the like may be issued in addition to displaying thedistance. With this, a driver (an operator) driving (operating) thevehicle (the transportation equipment) provided with the range imagingsystem 10 can be visually reminded of a danger.

Next, the following describes details on an example of the arrangementof the irradiation points, with reference to FIG. 24A, FIG. 24B, FIG.25A, and FIG. 25B.

FIG. 24A is a diagram showing an example of the arrangement in which thecenter of the irradiation region of the irradiation active light beamshas a small number of irradiation points while the periphery of theirradiation region has a large number of irradiation points. Thisexample of the arrangement is preferable particularly in the case wherethe vehicle (the transportation equipment) provided with the rangeimaging system 10 according to Embodiment 6 is currently moving andprioritizes the preceding object (the subject such as the precedingvehicle) and the surrounding objects in the distance measurement. Morespecifically, the range imaging system 10 can efficiently measure thefollowing: a distance to another vehicle (the preceding vehicle in FIG.24B) which is the subject travelling in front and located relatively faraway; and a distance to the subject (the traffic light in FIG. 25B)located near a road.

FIG. 25B is a diagram showing an example of the arrangement in which thedivided irradiation active light beams are emitted as lines instead ofspots. The shape of the irradiation active light (the laser light) canbe changed using, as an example, a line lens mentioned above. In thiscase, a distance to the subject that is relatively long horizontally orvertically in shape (in dimension), such as the traffic light or thestreet tree in FIG. 25B, can be measured accurately.

According to Embodiment 6, the shape of the irradiation active light maybe a combination of a spot shape as shown in FIG. 24A and FIG. 24B and alinear shape as shown in FIG. 25A and FIG. 25B. Alternatively, theirradiation active light may have a different shape.

In the range imaging system 10 shown in FIG. 21, the detection unit 80can detect (specify) the subject using the passive image signaloutputted from the solid-state imaging device 40 (the passive pixels)receiving the passive light, and output the signal (the movement controlsignal) based on the detection information to the pulsed-light sourceunit 20. This movement control signal is used for determining(selecting) the direction of the irradiation active light, thearrangement of the irradiation points, or the shapes of the irradiationactive light beams.

The arrangement of the irradiation points or the shapes of the laserlight beams can be changed using a single diffraction grating. Asanother method, a plurality of diffraction gratings may be provided asshown by the diffraction gratings 25 a and 25 b in FIG. 26A, which areselected as appropriate. As an example, such a change in the arrangementor shapes can be achieved by physically moving the light source 21, thediffraction grating 25 a, or the diffraction grating 25 b.

Alternatively, from among the plurality of diffraction gratings such asthe diffraction gratings 25 a and 25 b in FIG. 26B and the plurality ofcorresponding light sources such as the light sources 21 a and 21 b inFIG. 26B, the target light source and the corresponding diffractiongrating may be selected. This case has the advantage that the lightsource and the diffraction grating do not need to be physically moved.

In FIG. 26A and FIG. 26B, according to the aforementioned selection, thesubject can be detected using the passive image signal outputted fromthe solid-state imaging device 40 (the passive pixels) receiving thepassive light. On the basis of the detection information received as themovement control signal, the arrangement change of the irradiationpoints or the shape change of the irradiation active light beams can bedetermined (selected).

The range imaging system 10 according to Embodiment 6 described thus farwith reference to the drawings may have a configuration in which onlythe imaging signal is outputted from the imaging unit 30 (thesolid-state imaging device 40) as shown in FIG. 27.

Modification 1 of Embodiment 6

To facilitate understanding of Modification 1 of Embodiment 6, anexample of using a typical diffraction grating is described withreference to FIG. 28. FIG. 28 is a timing chart of a light emissionsignal and a plurality of irradiation active light beams divided by adiffraction grating 25 a from pulsed light emitted in response to thelight emission signal from a light source 21, in a typical system.

It should be noted that the following, as an example, are not taken intoconsideration to facilitate understanding of this example shown in FIG.28: a time delay from the issue of the light emission signal to theactual light emission; and a time (a time delay) taken for the emittedlight to reach a subject. Similarly, to facilitate understanding of thisexample, only two irradiation active light beams are shown in FIG. 28.Here, the irradiation active light beams a and b reach the correspondingirradiation points a and b in FIG. 22, FIG. 24A, or FIG. 24B.

As shown in FIG. 28, the light emission signal is issued at constantperiodic timings. On this account, the light beams divided by thediffraction grating cause interference with each other and thereby causea time lag in reaching the irradiation points. In FIG. 28, the lightbeams reaching the irradiation points a and b cause interference at theirradiation point b, at which a time lag from the issue of the lightemission signal is caused.

The simultaneous light emissions of the irradiation active light beams aand b cause interference, meaning that one of the irradiation activelight beams becomes an interfering light beams to the other. In the caseof regular pulse intervals, such interference occurs for each emissionof pulsed light. The time lag significantly decreases the accuracy ofthe measurement of the distance to the subject.

However, Modification 1 of Embodiment 6 can solve this problem. Detailson the solution is described with reference to FIG. 29 and FIG. 30. Asin the case of FIG. 28, the following, as an example, are not taken intoconsideration to facilitate understanding of examples shown in FIG. 29and FIG. 30: a time delay from the issue of the light emission signal tothe actual light emission; and a time (a time delay) taken for theemitted light to reach the subject. Similarly, to facilitateunderstanding of these examples, only two irradiation active light beamsare shown in FIG. 29 and FIG. 30. Here, the irradiation active lightbeams a and b reach the corresponding irradiation points a and b in FIG.22, FIG. 24A or FIG. 24B.

A first method is to issue the light emission signal at inconstantperiodic timings and emit the irradiation active light beams atinconstant periodic timings, as shown in FIG. 29. By this method,interference can be reduced even when the irradiation active light beamsa and b are being emitted simultaneously.

A second method is to divide the light emission signal into blocks inaccordance with the divided irradiation active light beams and to emitthe irradiation active light beams at individually unique timings asshown in FIG. 30. By this method, interference can be reduced more thanthe case shown in FIG. 28. More specifically, the unique emissiontimings can prevent the irradiation active light beams a and b frombeing emitted simultaneously and thus can further reduce interference.

As described thus far with reference to FIG. 29 and FIG. 30, the rangeimaging system in which the irradiation active light beams are emittedusing the diffraction grating can reduce a decrease caused in theranging accuracy by the interference between the irradiation activelight beams.

Modification 2 of Embodiment 6

FIG. 31 is an explanatory diagram showing an example in which sourcelight from a pulsed-light source unit 20 is divided into a plurality ofirradiation active light beams by a diffraction grating 25 a.

As shown in FIG. 31, a distance to a subject can be measured withreference to distance data that uses the spread of the divided lightbeams (irradiation active light beams a and b) by the same principle inFIG. 6 to FIG. 8. In FIG. 31, the spread of the irradiation active lightbeams by means of the diffraction grating 25 a is 5 cm of spread(dispersion) with respect to 1 m of distance to reach.

To be more specific, a distance L to the subject is calculated byExpression 2 below, where a distance between irradiation points isrepresented by d and the dispersion (the spread angle) of light isrepresented by θ.

d=L·tan θ  Expression 2

A range imaging system according to Modification 2 of Embodiment 6 canfurther improve the ranging accuracy by using data of, for example, thedistance between the irradiation points (the distance to the subject) asa correction value for the TOF range calculation or the image rangecalculation (Embodiments 4 and 5).

Although some exemplary embodiments of the present disclosure have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of the present disclosure. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure.

INDUSTRIAL APPLICABILITY

The range imaging system according to the present disclosure can measurea distance to a subject with high accuracy, and is thus useful inranging, for example, a person or a building.

1. A range imaging system comprising: a signal generation unitconfigured to generate a light emission signal for instructing lightirradiation and an exposure signal for instructing exposure; a lightsource unit including a light source and configured to emit anirradiation light beam in response to the light emission signal; animaging unit including a solid-state imaging device and configured toperform exposure and imaging in response to the exposure signal; and acalculation unit configured to calculate range information, wherein thesolid-state imaging device outputs an image capture signal for detectingan object and an imaging signal for calculating a distance, the lightsource unit is configured to irradiate an irradiation region with aplurality of the irradiation light beams divided from source lightoutputted from the light source, and the range information of the objectin the irradiation region is calculated using the image capture signaland the imaging signal based on light beams reflected from irradiationpoints on the object as a result of the light irradiation with theirradiation light beams reaching the irradiation points.
 2. The rangeimaging system according to claim 1, being mounted to transportationequipment, wherein the range information of the object present outsidethe transportation equipment and located in front of, behind, or on aside of the transportation equipment is calculated, and the object is anobstacle that obstructs driving of the transportation equipment.
 3. Therange imaging system according to claim 2, wherein the light source unitis provided in a front grille, a headlight, or a fog lamp of thetransportation equipment, and the imaging unit is provided near arearview mirror, in the front grille, or in a front bumper of thetransportation equipment.
 4. The range imaging system according to claim2, being provided near a license plate or in a sideview mirror sectionof the transportation equipment.
 5. The range imaging system accordingto claim 2, wherein the obstacle is another piece of transportationequipment or a person.
 6. The range imaging system according to claim 2,wherein at least a part of drive control of the transportation equipmentincluding the range imaging system is performed using the rangeinformation of the obstacle.
 7. The range imaging system according toclaim 1, wherein the irradiation region includes: a center region havinga small number of the irradiation points; and a peripheral region havinga large number of the irradiation points.
 8. The range imaging systemaccording to claim 7, wherein the center region of the irradiationregion includes an upper part having a small number of the irradiationpoints.
 9. The range imaging system according to claim 1, wherein thesolid-state imaging device includes a dual-purpose pixel for outputtingthe image capture signal and the imaging signal.
 10. The range imagingsystem according to claim 1, wherein the solid-state imaging deviceincludes a passive pixel for outputting the image capture signal and anactive pixel for outputting the imaging signal.
 11. The range imagingsystem according to claim 10, wherein the passive pixel receives visiblelight and the active pixel receives infrared light.
 12. The rangeimaging system according to claim 1, wherein the object is detectedusing the image capture signal and a distance to the object iscalculated as the range information using the imaging signal.
 13. Therange imaging system according to claim 1, wherein the light source is alaser light source, and the light source unit is configured to irradiatethe irradiation region with a plurality of laser light beams dividedfrom the source light.
 14. The range imaging system according to claim1, wherein the light source unit includes a diffraction grating, and thediffraction grating divides the source light into the irradiation lightbeams.
 15. The range imaging system according to claim 1, wherein eachof the irradiation light beams is emitted in a shape of a spot.
 16. Therange imaging system according to claim 1, wherein the calculation unitis configured to calculate a distance by a time-of-flight method.
 17. Arange imaging system comprising: a signal generation unit configured togenerate a light emission signal for instructing light irradiation andan exposure signal for instructing exposure; a light source unitincluding a light source and configured to emit an irradiation lightbeam in response to the light emission signal; an imaging unit includinga solid-state imaging device and configured to perform exposure andimaging in response to the exposure signal; and a calculation unitconfigured to calculate range information, wherein the solid-stateimaging device outputs an image capture signal and an imaging signal,and the image capture signal is used to detect an object in anirradiation region and the imaging signal is used to calculate adistance to the object in the irradiation region.
 18. A solid-stateimaging device that outputs an image capture signal and an imagingsignal, the solid-state imaging device being included in a range imagingsystem that includes: a signal generation unit configured to generate alight emission signal for instructing light irradiation and an exposuresignal for instructing exposure; a light source unit including a lightsource and configured to emit an irradiation light beam in response tothe light emission signal; an imaging unit including the solid-stateimaging device and configured to perform exposure and imaging inresponse to the exposure signal; and a calculation unit configured tocalculate range information, wherein the range imaging system irradiatesan irradiation region with a plurality of the irradiation light beamsdivided from source light outputted from the light source, andcalculates the range information of an object in the irradiation regionusing the image capture signal and the imaging signal based on lightbeams reflected from irradiation points on the object as a result of thelight irradiation with the irradiation light beams reaching theirradiation points.